Substitution.
Here is an example.
Let x be equal to 3 and y equal to 3.

From this we can conclude that the values of both x and y are equal to three therefore x and y have the same value and are equal.

Here in your case we have:

Hope this helps.
r3t40
a)0.43^5*0.57^5
b)0.43^6*0.57^4
c)0.43^3*0.57^7+0.43^2*0.57^8+0.43^1*0.57^9+0.57^10
See attached picture for steps and answer:
Hello there!
The answer is:
-5/8
-0.75
7/8